Extraction of ammonia from gases.



WALTHER FELD, OF I H O NNINGEN-ON-THE-RHINE, GERMANY.

EXTRACTIQN OF AMMONIA FROM GASE$.

Specification of Letters Patent.

Patented April '23, 1 907.

Application filed January 18, 1907. Serial No. 352,878.

To all whom it may concern."

Be it known that I, WALTnuR FELD, a l

subject of the King of Prussia and the German Emperor, of l[tinningen-on-the-Rhine, in the Kingdom of Prussia and the German Empire, have invented certain new and use ful Improvements in the Extraction of Ammonia from Gases, of which the following is a specification.

My invention has reference more especially to the process claimed in the specification of my United States Patent No. 830,983, and has for its object to extract ammonia. in a satisfactory and cllicient manner. in the form of ammonia salts (such, for instance, as sulfate oiiammonia, or chlorid of ammonia), from gases containing till1l114')I1i:l*--Su( li, for instance, as coal gas and the like.

Hitherto such gases have been cooled to a low temperature, the ammonia being partly dissolved by the water condensed from the gases at this low temperature, the other part of the ammonia, left in the gases alter the condensation of the water having al'tcrwards been extracted from the said gases by treatment with fresh water. From the dilute ammonia liouors thus obtained, the amn'ionia was distilled and absorbed by acids. In order to obviate the necessity for this distillation process, 'the gases have been treated with sull'uric acid at such a temperature (usually above 70 degrees centigrade) that practicaltv no water is condensed in the acid bath and the sulfuric acid is not diluted but the resulting sull'ate of ammonia is contan'iinated with tarry matters and contains sulfur, sulfuric acid and other impurities.

' According to my present invention, the ammonia is extracted from the gases by treating the gases with a liquor containing a calcium salt, which may be held entirely in solution, or partly in solution and partly in suspension. such. for instance. :isrlilorid ol lime, sulfate of lime and the like. The impure sullatc ol lime. as it occurs in nat ure and known in the trade as gypsum may be used and also the sull'ate ol lime obtained in many industries as a b v-product. it this treatment were etl'ectcd at a temperature above To degrees centigrrnle, the reaction would be slow and incomplete, and it it were. c'flcctml after the gases have cooled to under the dew-point of the water in the gases, the resulting solution of ammonia salt would be i l l l so diluted that distillation and absorption in acids would be necessary to obtain concentrated ammonia products. I therefore subject the gases to a preliminary treatment whereby the tar and the water are first removed in such a way that practically no no ammonia is condensed with either the tar or the water, and 1, then ell'eet the extraction of the ammonia "from the gases (from which the tar and water have been thus removed) by treating the said gases with a liquor conan insullicient proportion of carbon dioxid,

the proportion may be increased by passing air into the retorts in which the coal, or other gas-yielding material, is distilled, or water gas, or gases of combustion, or other gases containing carbon dioxid, may be added to'8o the'gases to be treated; and also the gases containing carbon dioxid may be subjected to the action of the liquor containing the calcium salt.

The following is an example of how my in- 5 vention may be carried into eil'ect, using the impure sulfate of lime, (known as gypsum), but 1 do not limit myself to this example, as I may use a calcium salt other than the impure sulfate and the proportions can be varied accort'ling to the nature of the gases to be treated and to the kind and concentration of the ammonia salts to be obtained.

The gases are first subjected to the treatment as described in the specification of my aforesaid United States Patent No. 830,983 or to equivalent treatment, whereby the tar and water are removed i'ronrthe gases without absorbing annnonia. .In order to a concentrated solution of sulfate of ammonia, 00

.1 mix 300 parts, by weight. of finely ground sull'atc ol" lime with 700 parts, by weight, of

water and the gases are treated with this liquor containing the sulfate partly in solution and partl -J' in suspension after the tar I05 and water have been removed from said gases as aforesaid. This treatment of the gases may be carried on 111 any sultable gaswashing apparatus. In order to extract all of the ammonia and to use practically all of the sulfate of lime in the alasorption process, at least two such apparatus should be used, or one apparatus with at least two chambers can be used, the lirst chamber containing the nearly saturated solution of sulfate of ammonia, and the second chamber'containing a l'resh. quantity of sulfate of lime held partly in solution and part1 in suspension.

The apparatus I prefer to use'is that described in the specification of my United States Patent No. 829,261, and containing several superposed chambers, or receptacles.

The fresh -liquor containing sulfate of lime, partly in solution and partly in suspension, enters atthe top, and the solution of suliate of ammonia containing the precipitate of calcium carhonatc together with any insoluble impurities contained in the sulfate of lime,.leavcs at the bottom. The gases pass through the apparatus in the opposite direction to that of the above liquor. By this treatment all the ammonia is absorbed and the saturated liquor, containing about 20 to 25 per cent. of sulfate of ammonia, is separatel from the precipitate oi carbonate of lime and evaporated to dryness. The 11-.- sulting sulfate of ammonia is neutral and practicallr iri irom impurities. The carbonate of lime can he washed with water and the washing liquors, containing dilute sulfate of ammonia, can be used instead of water, for mixing with the ground suliate of lime and therapy a more concentrated soluj molecular proportion 01' carbon dioxid to tion of sulfate of ammonia is obtained.

1 claim as my invention 1. The proc oi rxtracting ammonia from gasis, which consists in first sulijecting 5 such gas: water are emoved tnere'lrom, and then elto treatment by which tar and F fecting the extraction of the ammonia from the said gases by treating the said gases with a liquor containing a calcium salt.

2. The process of extracting ammonia from gases, which consists in first subjecting such gases to treatment by which tar and water are removed therefrom and then etlr-cting the extraction of the ammonia from the said gases b treating the said gases with sulfate 2 of lime held partly in solution and partljv in suspension.

3. Th s process of extracting'ammonia from gases, which consists in first sulijectiilig such to treatment by Wl11Cl1 tar and "a;

from gases produced from materials which are such that the gase molecular proportion of carbon dioxid to s contain less than one. i

two molecular proportions of ammonia, the said process consisting in introducing air into the distilling retorts and then lirst treating such gases so as to remove the tar and water and then effecting the extraction of am monia from the said gases by treating the said gases With a liquor containing a calcium salt.

ammonia from the said gases by treating thesaid gases with sulfateof lime, held partly in solution and partly in suspension. I

6. The process of extracting ammonia from gases produced from materials which are such that the gases contain less than one molecular proportion of carbon dioxid to two molecular proportions of ammonia, the said process consisting in introducing air into the distilling retorts and then first treat-- 111g such gases so as to remove the tar and water and then effecting the extraction of ammonia from the said gases by treating the said gases with gypsum, held partly in solution and partly in suspension.

7. The process of extracting ammonia from gases, produced trommaterials which are such that the gases contain less than one 1 two molecular proportions of ammonia, the

said process consisting in first subjecting such g: to treatment by which tar. and water are removed, and then effecting the extraction of ammonia from the produced gases b y subjecting such gases to treatment with a liquor containing a calcium salt, together with gases containing carbon dioxid.

8. The process of extracting ammonia from gases, produced from materials which are such that the gases contain less than one molecular proportion 'of carbon dioxid' to two molecular proportions ol ammonia, the said process consisting in first subjecting such gases to treatment by which tar and water are removed, and then efi'ecting the extraction of ammonia from the produced gases by srhgcctmg the said gases to treatment with sirllate ol lime, held partly in solrtion and partly in suspension, together i 1 1 witr gas containing caroon dioxld.

partly in solution and partly in suspen- 9. Ti. proccss of extracting ammonia from gases, produced from materials which are such tliat tle gases contain less than one molecular proportion of carbon dioxid to two molecular proportions of ammonia, the said process consisting in first suljecting such gases to treatmci'it by which tar and Water are removed, and then effecting the eX- name to this specification in the presence of traction of ammonia from the produced gases two subscribing Witnesses.

by subjectin the said ases to treatment with gypsuni; held part iy in solution and WALTHER FELD' 5 partly in suspension, together with gases i Witnesses:

containing carbon dioxid. HENRY HAsPER,

In testimony whereof I have signed my i WOLDEMAR HAUPT. 

